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testcritic

DeepSource vs Ruff

Feature checklists rarely decide anything. What decides it is the pricing metric, who has to write the tests, and which limitation you can live with.

Entry price

From $24 per user/month (Team, billed yearly)

Free tier

Free and open source

Open source

What drives the bill

The metric that actually scales your invoice.

Team includes a $100 annual AI Review credit per user; Enterprise adds self-hosting and SSO on a quote.

Free and open source. You pay in engineering time and CI minutes.

Free tier

Free for public repositories, with 1,000 PR reviews a month; 14-day trial plus AI Review credits on paid plans.

Everything, self-hosted

Open source

MIT

Self-hostable

No-code authoring

Languages

PythonJavaScriptTypeScriptGoJavaRubyPHPC#KotlinSwift
Python

Platforms

WebAPI
WebAPI

Fits teams

Solo / side projectStartupScale-up / mid-market
Solo / side projectStartupScale-up / mid-marketEnterprise

Adoption

Established

DeepSource · since 2019

Category standard

Astral · since 2022

Strengths

  • Autofix commits remove the tedious half of acting on findings.
  • Low false-positive rate keeps developers engaged with the tool.
  • Cheap and quick to adopt.
  • Replaces Flake8, isort, Black, pyupgrade and more with a single fast binary.
  • Fast enough to run on every keystroke in the editor.
  • Straightforward migration from existing Flake8 configurations.

Limitations

  • Narrower language coverage than SonarQube.
  • Smaller vendor with less enterprise governance tooling.
  • Autofix still needs review — it is not unattended.
  • Not every niche Flake8 plugin rule has been ported.
  • Type checking is a separate concern — you still need mypy or ty.
  • Rapid release cadence occasionally changes behaviour.

Best for

Teams that want static analysis developers do not resent.

Every Python project.

Pricing last reviewed August 2026 and is indicative only — confirm on each vendor’s own page.